Results 21 to 30 of about 37,815 (249)
A tool to understand emission mechanisms of blazars through their high‐energy gamma‐ray emission
Astronomische Nachrichten, Volume 344, Issue 6, August 2023., 2023 The blazar SED is characterized by two energy components. Evidence suggests that the low‐energy component is generated by the synchrotron mechanism, but for the high‐energy component, the mechanism is still uncertain. Two main models have been proposed to explain this emission. According to the leptonic model, a correlation between the emission of both
Mabel Osorio +3 more
wiley +1 more source
Supermassive Black Holes in Bulges [PDF]
The Astrophysical Journal, 2001 26 pages, 11 Postscript figures, accepted for publication on ...
Gregory Rudnick +9 more
openaire +4 more sources
Unraveling the enigmatic soft x‐ray excess: Current understanding and future perspectives
Astronomische Nachrichten, Volume 344, Issue 6, August 2023., 2023 Abstract This article explores various theoretical models proposed to explain the soft x‐ray excess phenomenon, including warm Comptonization, ionized reflection models, and ionized outflowing disc winds. The soft x‐ray excess is better understood thanks to crucial observations made by ROSAT, XMM‐Newton, and eROSITA.
Thomas Boller
wiley +1 more source
Energy Flux and Particle Flux in Steady-state Solutions of Nuclear Star Clusters
The Astrophysical Journal, 2023 We examine the effects of two-body interactions in a nuclear star cluster surrounding a supermassive black hole. We evaluate the energy flux, analogously to the particle flux calculation of Bahcall and Wolf.
Barak Rom, Itai Linial, Re’em Sari
doaj +1 more source
Multiwavelength astrophysics of the blazar OJ 287 and the project MOMO
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract We are carrying out the densest and longest multiyear, multiwavelength monitoring project of OJ 287 ever done. The project MOMO (Multiwavelength Observations and Modeling of OJ 287) covers wavelengths from the radio to the high‐energy regime. A few selected observations are simultaneous with those of the Event Horizon Telescope (EHT).
S. Komossa +21 more
wiley +1 more source
The Case for the Fundamental MBH-σ Relation
Frontiers in Physics, 2020 Strong scaling relations between host galaxy properties (such as stellar mass, bulge mass, luminosity, effective radius etc) and their nuclear supermassive black hole's mass point toward a close co-evolution.
Christopher Marsden +3 more
doaj +1 more source
Searching for overlooked TDEs in the 4XMM catalogue
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract Tidal disruption events (TDEs) are usually discovered as bright transients, either in the X‐ray or optical/UV band. These events are often characterized by a “super‐soft” emission in the X‐ray band, which has not been observed in any other extragalactic source, with few exceptions (novae and supersoft active galactic nuclei, AGN), which can ...
Andrea Sacchi +2 more
wiley +1 more source
A Global Inventory of Feedback
Galaxies, 2023 Feedback from both supermassive black holes and massive stars plays a fundamental role in the evolution of galaxies and the inter-galactic medium. In this paper, we use available data to estimate the total amount of kinetic energy and momentum created ...
Timothy M. Heckman, Philip N. Best
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Winds in ultraluminous X‐ray sources: New challenges
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract Ultraluminous X‐ray sources (ULXs) are extreme X‐ray binaries shining above 1039 erg/s, in most cases as a consequence of super‐Eddington accretion onto neutron stars and stellar‐mass black holes accreting above their Eddington limit. This was understood after the discovery of coherent pulsations, cyclotron lines, and powerful winds.
C. Pinto, P. Kosec
wiley +1 more source
Visible Shapes of Black Holes M87* and SgrA*
Universe, 2020 We review the physical origins for possible visible images of the supermassive black hole M87* in the galaxy M87 and SgrA* in the Milky Way Galaxy. The classical dark black hole shadow of the maximal size is visible in the case of luminous background ...
Vyacheslav I. Dokuchaev +1 more
doaj +1 more source